The visual system has been relatively neglected in recent MS research and often it is not even examined in autopsied patients. We propose to study demyelination of the optic nerve clinically and experimentally. We will record the visual evoked response (VER) and electroretinogram (ERG) in the rabbit eye to correlate the latency and amplitude of the VER with the normal time course of myelination of epiretinal optic nerve fibers. Rabbits with Experiment Allergic Optic Neuritis will also be recorded in an attempt to correlate the clinical and histologic changes of in vivo demyelination of the visual system with alternations in the VER and E RG.